A heat sink placed in contact with an electronic device transfers heat through conduction from the semi-conductor device contained in the electronic package. U.S. Pat. No. 4,884,331--Hinshaw shows a commonly used pin fin heat sink used to dissipate the conducted heat.
Springs or clips, such as those shown in U.S. Pat. No. 4,745,456--Clemens, or U.S. Pat. No. 4,660,123--Hermann, have been used to secure heat sinks to electronic devices, and a catalog entitled "Thermalloy Semiconductor Accessories," pp. 15-29, Thermalloy, Inc., Dallas, Tex. (USA) also shows clips for attaching heat sinks to electronic devices. Page 17 of the Thermalloy catalog shows two types of wire springs for securing a heat sink to a pin grid array (PGA). Co-pending application Ser. No. 349,672, filed Dec. 5, 1994, "Strap For Heat Sink Clip Assembly," shows and describes several different clips for securing a heat sink to an electronic device. Another type of anchor for securing a heat sink to a printed circuit board is shown in co-pending application Ser. No. 08/477,794 filed Jun. 7, 1995. Both of these co-pending applications are incorporated herein by reference as if set forth in their entirety.
However, if a heat sink is larger than the microprocessor there is no secure way to attach the heat sink to the microprocessor. The microprocessor is typically, but not necessarily, a socket. Surface mount applications for Ball Grid Array (BGA), Column Grid Array (CGA), Land Grid Array (LGA), Plastic Quad Flat Pack (PQFP), are all examples of devices that are not in sockets.
In the above-mentioned prior art attachment means, which clip the heat sink to the circuit board, the circuit boards often warp due to the spring loading by the attachment device. Therefore, devices that provide attachment to the board normally have to be kept close to the microprocessor, so that the board is not put under large bending stresses. Also, some prior art clips require a soldering operation to affix the hook in the board. This usually would be a wave soldering operation, which is not normally done when surface mount technology is used.
It is therefore an object of the present invention to provide an anchor which can be inserted through a printed circuit board to secure a heat sink and an electronic device to the board.